1. Field of the Invention
This invention relates to a sealing element for use in sealing openings in fire-protective structures such as fire walls.
2. The Prior Art
In order to seal connecting joints, expansion joints, etc., in fire breaks, fire walls and wall break-throughs (compare also DIN 4012), it has long been known to use agents based on asbestos, such as the tradenamed product "Litaflex," or heat-expanding sealing compounds, e.g., Foamox. It is also known to insert asbestos in the form of an asbestos braid into such joints.
Such conventional sealing elements have various drawbacks. First of all, it is now known that asbestos materials are hazardous, and thus their use is to be avoided, if possible. In addition, known sealing elements may not achieve a satisfactory seat in the joints, which of course is extremely unsatisfactory since even one location where the heat or flames can penetrate destroys the effectiveness of the fire protection. In the case of joints of irregular width, the known sealing elements can be processed only with great difficulty. Moreover, a time-consuming edge pretreatment of the joints is necessary. In addition (and especially important), whether there is enough asbestos compound or heat-expanding sealing compound in the protecting joints is not controllable. And on the whole, the known sealing elements are quite expensive, not only because of the aforementioned circumstances but also due to their manufacturing costs.
On the other hand, the use of precompressed or precompacted foam tapes has been known for a long time for sealing joints in the construction industry. See, for example, Plastics in Construction, Vol. 15, 1980, issue 2, pages 66 to 68. See also U.S. Pat. Nos. 4,621,731 and 4,401,716. However, even if the precompressed foamed tape is impregnated, e.g., with a mixture of chloroparaffin and neoprene so as to provide for a delayed restoration and a flame-retardant property, there is no possibility of using such foam tapes when subjected to high temperatures in the range of about 800.degree. C. because at temperatures above about 200.degree. C. the foam begins to melt and vaporize.
The object of the present invention is therefore to design and further develop the known sealing elements for walls, wall break-throughs or the like, which are subject to special fire-protection requirements in such a manner that greater fire-protection is achieved and production and processibility are more cost effective.